1. Field of the Invention
The present invention relates to an air-tight structure between a top cap and a body of a pneumatic tool.
2. Description of the Related Art
A conventional pneumatic tool is shown in FIG. 1 and generally includes a top cap 10 and a tool body 11 which includes a movable shaft 110 retractably received in a tubular part of the tool body 11. The removable shaft 110 is actuated by pneumatic power. An air-tight structure is employed to obtain an air sealing feature between the top cap 10 and the tool body 11. The air-tight structure includes a metal plate 16 located between the top cap 10 and the tool body 11, a rubber seal 15 is engaged with the metal plate 16 so as to seal the abutting surface between the top cap 10 and the tool body 11. The rubber seal 15 tends to be scraped and broken when connecting the top cap 10 and the tool body 11. The metal plate 16 is easily deformed and air leakage between the top cap 10 and the tool body 11 can result. Although the rubber seal 15 is replaced by a PU seal in some pneumatic tools, the PU-made seal is fitted into the top cap 10 by a large force which might affect the combination of the parts of the tool. Besides, the top cap 10 is fixedly connected to the tool body 11 by extending bolts from a top of the top cap 10 and engaged with the tool body 11. Therefore, there are a plurality of sink holes defined in the top of the top cap and the sink holes make the user's hands uncomfortable.